The invention concerns a method for operating an X-ray analysis device with an X-ray radiation source, an object under investigation which is irradiated with X-ray radiation, and a planar two-dimensional array detector with pixel elements for locally resolved detection of the X-ray radiation emitted by the object, wherein a data set is obtained, in particular, in the form of a digitized diffractogram and/or spectrum. The invention also concerns an X-ray analysis device for carrying out the method.
Two-dimensional array detectors, which are used in X-ray analysis devices of the above-mentioned type, are known i.a. from Gerhard Lutz “Semi-conductor radiation detectors”, B. Mikulec et al. “Development of Segmented Semiconductor Arrays for Quantum Imaging” Elsevier Science, N. Wermes “Pixel detectors for particle physics and imaging applications” Elsevier Science Direct and Edwin M. Westbrook National Institute of Health Förderantrag www.brunel.ac.uk/research/rose/3D/publications.html. These array detectors consist of a plurality of photo-sensitive pixel elements which are arranged in the form of an array on a chip. The sensor chip is usually in bump bonding contact with an ASIC (Application Specific Circuit), which comprises electronic channels, amplifiers and discriminators. Since the photo-sensitive pixel elements are integrally connected to the ASIC, exchange of a faulty pixel element is not possible. Faulty, in particular, blind pixel elements represent a substantial technical problem. Attempts have been made to reduce the number of blind pixel elements through manufacturing improvements. Due to the large complexity of the hybrid production (sensor, bump bonds, highly integrated ASIC), only very expensive pixel detectors with 100% functionality will be available in the near future. One usually accepts the existence of individual blind pixel elements and the resulting missing information in the corresponding regions.
To avoid the resulting disturbing effect of e.g. black image regions (dead pixels), several pixels are conventionally combined into one super pixel. This method, however, reduces the resolution of the associated measurements. If effects on the size of one pixel element are to be observed, individual blind pixel elements can seriously falsify the data, since precisely those dead pixel regions could contain important information.
In addition to two-dimensional array detectors, one-dimensional detectors are also disclosed (H. Göbel, Adv. in X-Ray Analysis 22 (1978) 255–265) which can be displaced using a goniometer through changing the 2Θ value over the region which is of interest for the measurement and permit detection of differing measuring regions by different pixels. However, these methods only permit one-dimensional recordings. Moreover, the optics for focussing the radiation onto the detector must be displaced along with the detector, which disadvantageously requires the structure of the arrangement to be particularly stable.
It is therefore the underlying purpose of the present invention to propose a method for operating an X-ray analysis device having a two-dimensional array detector with pixel elements which reduces the number of or eliminates dead pixels in the data set despite the presence of blind pixel elements in the detector to thereby obtain as complete a data set as possible as well as an X-ray analysis device for carrying out this method.